Three-way valve

Abstract

To suppress deterioration of joint strength between a driving member and a shaft caused by adhesion of grease applied to a male screw part of the driving member to a tip of the shaft when assembling a three-way valve.SOLUTION: In a three-way valve, a third port is communicated with the middle of a linear channel in which a first port is communicated with one end and a second port is communicated with the other end, and opening areas of a first valve port and a second valve port of the linear channel are changed by the movement of a first valve body 34a and a second valve body 34b corresponding to each other, arranged at a lower end of a shaft 35. The shaft is passed through a bearing part 42 of a guide 41, and its upper end is inserted and connected to the inside of a cylindrical driving member 50. The driving member has a gear part 51 at an upper end side of an outer peripheral surface, and has a male screw part 53 having a male screw formed on a lower end side. The guide has a female screw part 43 having a female screw formed on an inner peripheral surface above the bearing part, and the male screw part is screwed with the female screw part. A cylindrical part 54 having an outer diameter smaller than an inner diameter of the female screw part is projected downward from a lower end surface of the female screw part in the driving member.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a three-way valve having a first port connected to one end and a second port connected to the other end of a straight flow path, with a third port connected to the middle of the straight flow path, and capable of changing the amount of fluid flowing between the first port and the third port, and the amount of fluid flowing between the second port and the third port. [Background technology]

[0002] Three-way valves with three ports for connecting pipes are widely used in water heaters and other appliances, such as as a dividing valve that can divide the flow of a fluid, such as water, from one pipe to two pipes to change the dividing ratio, or as a mixing valve that can combine the flow of a fluid from two pipes to one pipe to change the mixing ratio. For example, in Patent Document 1, a three-way valve used as a dividing valve in a water heater has a first port connected to one end of a linear flow passage formed in a casing, a second port connected to the other end, and a third port connected to the middle of the linear flow passage. A first valve port is provided between the first and third ports in the linear flow passage, and the opening area of ​​the first valve port changes as the first valve body approaches or moves away from the first port. Similarly, a second valve port is provided between the second and third ports, and the opening area of ​​the second valve port changes as the second valve body approaches or moves away from the second port. The first valve body and the second valve body are joined to the end of a shaft that can be moved in an axial direction parallel to the linear flow path by driving a motor, and the first valve body and the second valve body move along the linear flow path together with the shaft, thereby changing the flow rate of fluid between the first port and the third port, and the flow rate of fluid between the second port and the third port.

[0003] This shaft is inserted into a bearing portion of an inner member incorporated into the casing of the three-way valve as a guide and supported so as to be movable axially, and its end opposite the first and second valve bodies is inserted into and joined to the inside of a drive member, which has a gear portion formed on its outer peripheral surface to which drive from the motor is transmitted. If the valve body side of the shaft is positioned downward and the drive member side is positioned upward in the axial direction, the drive member has a gear portion on the upper end side of its outer peripheral surface and a male thread portion formed with a male thread on its lower end. Meanwhile, the inner member has a female thread portion above the bearing portion, with a female thread formed on its inner peripheral surface that corresponds to the male thread portion, and the male thread portion and the female thread portion are threadedly engaged. When the drive member is rotated around the axis of the shaft by the drive of the motor, the shaft moves axially together with the drive member as the male thread portion and the female thread portion engage with each other. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-62559 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in three-way valves having the above-described configuration, grease is often applied to the male threaded portion of the drive member during the assembly process to lubricate the threaded engagement between the male threaded portion of the drive member and the female threaded portion of the inner member.If this grease adheres to the end surface of the male threaded side of the drive member, the grease may adhere to the tip of the shaft when it is inserted inside the drive member, which can cause a problem in that the presence of grease can reduce the joint strength between the drive member and the shaft.

[0006] This invention has been made in response to the above-mentioned problems in the conventional technology, and aims to provide a technology that can suppress a decrease in the joint strength between the drive member and the shaft caused by grease applied to the male thread portion of the drive member adhering to the tip of the shaft during the process of assembling the three-way valve. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the three-way valve of the present invention employs the following configuration: <First aspect> a three-way valve having a straight flow passage having one end communicating with a first port and the other end communicating with a second port, the straight flow passage having an opening area of ​​a first valve orifice provided between the first port and the third port changing as a first valve disc approaches or moves away from the straight flow passage, and an opening area of ​​a second valve orifice provided between the second port and the third port changing as a second valve disc approaches or moves away from the straight flow passage; the first valve disc and the second valve disc are disposed at an end of a shaft that is movable in an axial direction parallel to the straight flow passage by being driven by a motor; and the first valve disc and the second valve disc move along the straight flow passage together with the shaft, thereby changing the flow rate of fluid between the first port and the third port and the flow rate of fluid between the second port and the third port; a guide provided with a bearing portion through which the shaft is inserted and supporting the shaft so that the shaft is movable in the axial direction; a cylindrical driving member having a gear portion formed on an outer circumferential surface to which the drive of the motor is transmitted, and an end of the shaft opposite to the first valve body and the second valve body is inserted into and joined to an insertion hole opened in an end surface facing the first valve body and the second valve body; Equipped with Assuming that the drive member side of the shaft in the axial direction is the upper side and the opposite side where the first valve body and the second valve body are arranged is the lower side, The drive member has a male threaded portion below the gear portion, the male threaded portion having a male thread formed on an outer peripheral surface thereof, and the guide has a female threaded portion above the bearing portion, the female threaded portion having a female thread formed on an inner peripheral surface thereof, When the driving member rotates around the axis of the shaft by driving the motor while the male screw portion and the female screw portion are threadedly engaged with each other, the shaft moves in the axial direction in accordance with the engagement of the male screw portion and the female screw portion, A cylindrical portion having an outer diameter smaller than the inner diameter of the female thread portion and having the insertion hole on the inside thereof is protruded downward from the lower end surface of the male thread portion of the driving member. It is characterized by:

[0008] In the three-way valve of the first aspect, by interposing a cylindrical portion between the male thread portion on the outer peripheral surface of the drive member and the lower end surface (the end surface facing the first valve body and the second valve body) where the insertion hole opens, grease applied to the male thread portion is less likely to adhere to the periphery of the insertion hole on the lower end surface of the drive member (cylindrical portion) compared to when there is no cylindrical portion, and therefore it is possible to prevent grease from adhering to the tip of the shaft when inserting the tip of the shaft into the insertion hole of the drive member. As a result, it is possible to prevent a decrease in the joint strength between the drive member and the shaft due to grease adhesion.

[0009] <Second aspect> In the three-way valve of the first aspect, The shaft is formed with a rotation prevention portion having a non-circular cross section perpendicular to the axial direction, a fitting portion having a shape that corresponds to the anti-rotation shape and fits with the anti-rotation portion is provided as part of the insertion hole on the inside of the cylindrical portion of the driving member, an upper end of the anti-rotation portion is located lower than an upper end of the female screw portion when the axial movement of the shaft inserted into the bearing portion of the guide reaches an upper limit; The cylindrical portion of the driving member is provided to protrude to a length that allows the fitting portion to fit into the anti-rotation portion before the male screw portion and the female screw portion are screwed together. It is characterized by:

[0010] In this type of three-way valve of the second embodiment, the drive member, which has a cylindrical portion inserted inside the female threaded portion, can be freely rotated around the axis of the shaft without being restricted by the threaded engagement between the male threaded portion and the female threaded portion, allowing the engagement between the anti-rotation portion and the engaging portion to be aligned, making assembly easier than when there is no cylindrical portion.

[0011] <Third aspect> In the three-way valve of the second aspect, a groove in which an O-ring is fitted to seal the gap between the shaft and the bearing portion of the guide is formed on the outer circumferential surface of the shaft; The groove is formed at a position where the O-ring is positioned below a lower end of the female screw portion when the axial movement of the shaft inserted into the bearing portion of the guide reaches an upper limit and the upper end of the anti-rotation portion is positioned below an upper end of the female screw portion. It is characterized by:

[0012] In the three-way valve of the third aspect, by fixing the O-ring to the shaft side, it is possible to omit the backup ring or retaining ring that would be required if the O-ring were fixed to the bearing side of the guide, thereby reducing the number of parts in the three-way valve and simplifying assembly. Furthermore, even if the O-ring moves axially together with the shaft, the O-ring will not protrude toward the female threaded portion when the shaft reaches its upper limit of movement, thereby preventing the O-ring from being damaged by contact with the boundary between the bearing portion and the female threaded portion or the female thread, etc. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is an explanatory diagram illustrating the overall configuration of a water heater 1 equipped with a three-way valve 26 of the present embodiment. [Figure 2] 2 is a cross-sectional view showing the internal structure of a three-way valve 26 of the present embodiment. FIG. [Figure 3] FIG. 2 is an exploded perspective view of the three-way valve 26 of the present embodiment. [Figure 4] 10 is an explanatory diagram comparing the ease with which grease adheres to the tip of the small diameter portion 35a of the shaft 35 between when the driving member 50 does not have a cylindrical portion 54 and when it does have one. FIG. [Figure 5] This is an explanatory diagram showing the assembly sequence of the three-way valve 26, in which the shaft 35 of the shaft valve body 36 is inserted into the bearing portion 42 of the guide 41, and then the male thread portion 53 of the drive member 50 is screwed into the female thread portion 43 of the guide 41. DETAILED DESCRIPTION OF THE INVENTION

[0014] FIG. 1 is an explanatory diagram illustrating the overall configuration of a water heater 1 equipped with a three-way valve 26 of this embodiment. As shown in the figure, the water heater 1 is equipped with a burner 3 housed in a combustion chamber 2 for burning fuel gas, and a gas pipe 4 for supplying the fuel gas is equipped with a main valve 5 for opening and closing the gas pipe 4 and a proportional valve 6 for adjusting the flow rate of the fuel gas. The water heater 1 is also equipped with a combustion fan 10 that sends combustion air from below toward the burner 3, an ignition plug 11 that ignites the burner 3 by spark discharge, and a flame rod 12 that detects the flame (ignition) of the burner 3. The rotation speed of the combustion fan 10 can be controlled according to the opening of the proportional valve 6, thereby adjusting the air-fuel ratio to a predetermined value.

[0015] A heat exchanger 13 is provided above the burner 3, and the combustion exhaust gas generated by combustion in the burner 3 is sent upward by the air blown by the combustion fan 10, and after passing through the heat exchanger 13, is discharged to the outside from an exhaust port 14 at the top of the water heater 1. A water supply pipe 20 that supplies clean water is connected to one end (upstream side) of the heat exchanger 13, and a hot water supply pipe 21 is connected to the other end (downstream side) of the heat exchanger 13. In addition, in the water heater 1 of this embodiment, the water supply pipe 20 and the hot water supply pipe 21 are connected by a bypass pipe 22. Hereinafter, the upstream side of the connection position of the water supply pipe 20 with the bypass pipe 22 may be referred to as the "upstream water supply pipe 20a," and the downstream side of the connection position may be referred to as the "downstream water supply pipe 20b."

[0016] The upstream water supply pipe 20a is provided with, in order from upstream, a water supply temperature sensor 23 that detects the temperature of the clean water being supplied, a flow rate sensor 24 that detects the flow rate of the clean water, and a water volume servo 25 that opens and closes the upstream water supply pipe 20a and controls the flow rate. A three-way valve 26 is provided at the connection point between the water supply pipe 20 and the bypass pipe 22. Details of the three-way valve 26 will be described later using a separate drawing. In this embodiment, the three-way valve 26 is used as a flow dividing valve that divides the flow of clean water supplied to the water heater 1 into a flow that is supplied to the heat exchanger 13 and a flow that passes through the bypass pipe 22 without being supplied to the heat exchanger 13, and is capable of changing the amount of water passing through the heat exchanger 13 and the bypass pipe 22.

[0017] The clean water supplied to the heat exchanger 13 is heated in the heat exchanger 13 by heat exchange with the exhaust gas from the burner 3, and becomes hot water, which flows out into the hot water supply pipe 21. The hot water that flows out into the hot water supply pipe 21 is then mixed with the clean water that has passed through the bypass pipe 22, and is supplied to a bathtub or hot water tap (not shown). The mixing ratio of the hot water heated in the heat exchanger 13 and the clean water that has passed through the bypass pipe 22 can be changed by the three-way valve 26.

[0018] The hot water supply pipe 21 is provided with an outlet hot water temperature sensor 27 that detects the temperature of the hot water immediately after it flows out of the heat exchanger 13, and a hot water supply temperature sensor 28 that detects the temperature of the hot water mixed with the clean water downstream of the connection position with the bypass pipe 22 (hot water supply temperature). Naturally, the temperature detected by the hot water supply temperature sensor 28 is lower than the temperature detected by the outlet hot water temperature sensor 27, and by adjusting the mixing ratio of the hot water heated in the heat exchanger 13 and the clean water that has passed through the bypass pipe 22 with the three-way valve 26, it is possible to suppress fluctuations in the hot water supply temperature (the temperature of the hot water supplied to the bathtub and hot water tap).

[0019] 2 is a cross-sectional view showing the internal structure of three-way valve 26 of this embodiment. As shown in the figure, three-way valve 26 has a first port 32a connected to one end of straight flow path 31 formed in casing 30, a second port 32b connected to the other end, and a third port 32c connected to the middle of straight flow path 31. In water heater 1 of this embodiment, downstream water supply pipe 20b is connected to first port 32a, bypass pipe 22 is connected to second port 32b, and upstream water supply pipe 20a is connected to third port 32c (see FIG. 1).

[0020] Furthermore, a substantially circular first valve port 33a is provided between the first port 32a and the third port 32c in the straight flow path 31, and the opening area of ​​the first valve port 33a changes as a first valve element 34a, which has a tapered shape and decreases in diameter toward the first valve port 33a, moves closer to or away from the first valve port 33a. Similarly, a substantially circular second valve port 33b is provided between the second port 32b and the third port 32c in the straight flow path 31, and the opening area of ​​the second valve port 33b changes as a second valve element 34b, which has a tapered shape and decreases in diameter toward the second valve port 33b, moves closer to or away from the second valve port 33b. The first valve element 34a and the second valve element 34b are disposed at one end of a shaft 35 that is movable in an axial direction parallel to the straight flow path 31 by driving a motor (not shown). 2, the explanation will be given assuming that the axial direction of the shaft 35 is arranged in the up-down direction (vertical direction), with one end where the first valve body 34a and the second valve body 34b are arranged being the lower end and the other end being the upper end. However, the installation direction of the three-way valve 26 is not limited to this, and it is also possible to use the three-way valve 26 with the axial direction of the shaft 35 arranged horizontally.

[0021] The first valve body 34a and the second valve body 34b move along the linear flow path 31 in conjunction with the shaft 35, thereby changing the flow rate of fluid (water flow rate in this embodiment) between the first port 32a and the third port 32c and the flow rate of fluid between the second port 32b and the third port 32c. For example, when the shaft 35 moves upward, the opening area of ​​the first valve orifice 33a becomes smaller as the first valve body 34a approaches, thereby decreasing the flow rate of water between the first port 32a and the third port 32c. At the same time, the opening area of ​​the second valve orifice 33b becomes larger as the second valve body 34b moves away, thereby increasing the flow rate of water between the second port 32b and the third port 32c. Conversely, when the shaft 35 moves downward, the opening area of ​​the first valve port 33a increases as the first valve body 34a moves away, increasing the amount of water flowing between the first port 32a and the third port 32c. At the same time, the opening area of ​​the second valve port 33b decreases as the second valve body 34b moves closer, decreasing the amount of water flowing between the second port 32b and the third port 32c.

[0022] An inner member 40 having a guide 41 (described later) is assembled in the upper part of the casing 30, and the shaft 35 is inserted into a bearing portion 42 of the guide 41 and journaled so as to be movable in the axial direction (the up-down direction in the drawing). The tip (upper end in the drawing) of the shaft 35 opposite the first valve body 34a and the second valve body 34b is inserted into the inside of a cylindrical driving member 50 having a gear portion 51 (described later) formed on the outer circumferential surface to which the drive force of the motor is transmitted, and joined by thermal welding.

[0023] Furthermore, as shown in the figure, a cover plate 60 is installed to cover the top of the casing 30 in which the inner member 40 is assembled, and the top of the guide 41 protrudes upward from a through-hole 60a in the cover plate 60. A motor case 61 is attached above the cover plate 60, and contains a motor and a mechanism (not shown) for transmitting the drive of the motor. The drive member 50, which is joined to the tip of the shaft 35, is disposed within the motor case 61.

[0024] Fig. 3 is a perspective view showing the three-way valve 26 of this embodiment in an exploded state. Note that Fig. 3 does not show the casing 30, the cover plate 60, and the motor case 61. First, in the three-way valve 26 of this embodiment, the first valve body 34a, the second valve body 34b, and the shaft 35 are integrally formed as the shaft valve body 36, and as described above, the first valve body 34a and the second valve body 34b are disposed at the end (the lower end in the figure) of the shaft 35.

[0025] As shown in the figure, the shaft 35 does not have a uniform diameter but has three different diameters. The smallest diameter section 35a is located at the upper end where the drive member 50 is attached. The largest diameter section 35c is located at the lower end where the valve bodies 34a and 34b are formed. A medium diameter section 35b of intermediate thickness is located between the small diameter section 35a and the large diameter section 35c. The small diameter section 35a and the large diameter section 35c have substantially circular cross sections perpendicular to the axial direction of the shaft 35, whereas the medium diameter section 35b has a non-circular anti-rotation shape. In this embodiment, the cross section is an I-cut shape formed by removing two flat surfaces parallel to the axial direction from the cylindrical circumferential surface. The anti-rotation shape of the medium diameter section 35b is not limited to an I-cut shape and may be a D-cut shape formed by removing one flat surface in the axial direction from the cylindrical circumferential surface. In this embodiment, the medium diameter section 35b corresponds to the "anti-rotation section" of the present invention.

[0026] Two circumferential grooves 35d are provided axially apart on the outer peripheral surface of the large diameter portion 35c, and O-rings 37 are fitted into the grooves. The O-rings 37 ensure a tight seal between the outer peripheral surface of the large diameter portion 35c and the inner peripheral surface of the bearing 42 when the shaft 35 is inserted into the bearing 42 of the guide 41.

[0027] In addition, the axial valve body 36 of this embodiment has a plurality of (three in this embodiment) guide portions 38 that protrude downward (the opposite side to the drive member 50) from the second valve body 34b and are arranged approximately evenly in the circumferential direction. By inserting these plurality of guide portions 38 into the second valve port 33b, vibration of the axial valve body 36 in the axial direction of the shaft 35 is suppressed, thereby improving the accuracy of movement of the first valve body 34a and the second valve body 34b.

[0028] Furthermore, the shaft valve body 36 of this embodiment has a plurality of (four in this embodiment) protrusions 39 that protrude upward (toward the drive member 50) from the first valve body 34a and are arranged approximately evenly around the large diameter portion 35c. As will be described later, these plurality of protrusions 39 come into contact with the lower end (the end facing the first valve body 34a) of the bearing portion 42 of the guide 41, thereby restricting the upper limit of axial movement of the shaft 35 (the limit of movement toward the drive member 50).

[0029] Next, the inner member 40 of this embodiment is formed by integrally forming a guide 41 provided with a bearing portion 42 and a valve seat 45 formed with a first valve port 33a via a connecting portion 46. In Figure 3, the inner member 40 is cut along a plane including the center line of the bearing portion 42 so that the inside of the bearing portion 42 can be seen. The shaft 35 of the stem valve element 36 is inserted into the bearing portion 42 of the guide 41 through the first valve port 33a of the valve seat 45.

[0030] Bearing portion 42 is generally cylindrical, and when shaft 35 is inserted as described above, O-ring 37 seals the gap between the outer circumferential surface of large diameter portion 35c and the inner circumferential surface of bearing portion 42. That is, O-ring 37, which is attached to groove 35d in the outer circumferential surface of large diameter portion 35c, moves inside bearing portion 42 together with shaft 35. By fixing O-ring 37 to shaft 35 in this way, it is possible to omit a backup ring, a retaining ring, and the like that would be required when fixing O-ring 37 to bearing portion 42 of guide 41, thereby reducing the number of parts of three-way valve 26 and simplifying assembly.

[0031] As described above, upward movement of the stem valve body 36 is restricted when the protrusion 39 of the stem valve body 36 abuts against the lower end of the bearing portion 42. As shown in the drawing, above the bearing portion 42 in the guide 41 (on the drive member 50 side), there is provided a female thread portion 43 having a female thread formed on the inner peripheral surface.

[0032] The drive member 50 of this embodiment has a gear portion 51 formed on the outer circumferential surface of a cylindrical shape to which the drive force of the motor is transmitted, and an insertion hole 52 for inserting the small-diameter portion 35a of the shaft 35 therein. A fitting portion 52a is provided at the lower end of the insertion hole 52 (the side facing the first valve body 34a) so as to fit with the medium-diameter portion 35b in accordance with the anti-rotation shape of the medium-diameter portion 35b. The engagement between the fitting portion 52a and the medium-diameter portion 35b prevents rotation of the drive member 50 and the shaft 35. The upper end of the insertion hole 52 has a substantially circular cross section perpendicular to the axial direction, corresponding to the small-diameter portion 35a. The insertion hole 52 of this embodiment penetrates the drive member 50 in the vertical direction, and the tip of the small-diameter portion 35a of the shaft 35 inserted from the fitting portion 52a side protrudes from the opposite side of the insertion hole 52 and is joined by infrared heat welding.

[0033] Further, below the gear portion 51 on the outer peripheral surface of the driving member 50, a male threaded portion 53 is provided, on which a male thread corresponding to the female threaded portion 43 of the guide 41 is formed. Furthermore, a cylindrical portion 54 having an outer diameter smaller than the inner diameter of the female threaded portion 43 protrudes downward from the lower end surface of the male threaded portion 53, and a fitting portion 52a is provided inside this cylindrical portion 54 as a part of the insertion hole 52.

[0034] The male thread portion 53 of the drive member 50 is threadedly engaged with the female thread portion 43 of the guide 41, and when the drive member 50 rotates around the axis of the shaft 35 due to the driving of the motor, the shaft 35 moves axially together with the drive member 50 relative to the guide 41 in accordance with the engagement of the male thread portion 53 and the female thread portion 43.

[0035] In the three-way valve 26 described above, grease is typically applied to the male thread portion 53 of the drive member 50 during assembly to lubricate the threaded engagement between the male thread portion 53 of the drive member 50 and the female thread portion 43 of the guide 41. However, if grease adheres to the tip of the small diameter portion 35a of the shaft 35 when the small diameter portion 35a is inserted into the insertion hole 52 of the drive member 50, the presence of the grease may reduce the bonding strength between the drive member 50 and the shaft 35. Therefore, in the three-way valve 26 of this embodiment, the drive member 50 is provided with a cylindrical portion 54, which prevents the grease applied to the male thread portion 53 of the drive member 50 from adhering to the tip of the small diameter portion 35a of the shaft 35. This point will be explained below in comparison with a case in which the drive member 50 does not include the cylindrical portion 54.

[0036] 4A and 4B are explanatory diagrams comparing the ease with which grease adheres to the tip of the small diameter portion 35a of the shaft 35 when the drive member 50 does not include the cylindrical portion 54 and when it does include the cylindrical portion 54. FIG. 4A shows a cross section of the drive member 50 cut along a plane including the center line of the insertion hole 52, and FIGS. 4A and 4B show a case in which the drive member 50 does not include the cylindrical portion 54. As shown in FIG. 4A, when grease G applied to the male thread portion 53 of the drive member 50 spills from the outer peripheral surface of the male thread portion 53 onto the lower end surface of the drive member 50 (the end surface facing the first valve body 34a), the grease G adheres to the periphery of the insertion hole 52 because the insertion hole 52 (fitting portion 52a) opens on the same lower end surface.

[0037] 4(b), when the male thread portion 53 of the drive member 50, to which grease G has been applied, is threaded into the female thread portion 43 of the guide 41 and moved to the innermost part of the female thread portion 43, the grease G spilling out from between the male thread portion 53 and the female thread portion 43 is pushed out onto the lower end face of the drive member 50 and adheres to the periphery of the insertion hole 52 (fitting portion 52a) opening on the same lower end face. Then, when the small diameter portion 35a of the shaft 35 inserted into the bearing portion 42 of the guide 41 is inserted into the insertion hole 52 of the drive member 50, the grease G adhering to the periphery of the insertion hole 52 may adhere to the tip of the small diameter portion 35a.

[0038] 4(c) and 4(d) show a case where the driving member 50 is provided with a cylindrical portion 54. As shown in Fig. 4(c), even if the grease G applied to the male thread portion 53 of the driving member 50 overflows from the outer peripheral surface of the male thread portion 53, since the cylindrical portion 54 protrudes downward from the lower end of the male thread portion 53, the grease G may adhere to the outer peripheral surface of the cylindrical portion 54, but the grease G is less likely to adhere to the lower end surface (the end surface facing the first valve body 34a) of the cylindrical portion 54 where the insertion hole 52 (fitting portion 52a) opens.

[0039] Furthermore, as shown enlarged in Figure 4(d), when the male threaded portion 53 of the drive member 50, to which grease G has been applied, is screwed all the way into the female threaded portion 43 of the guide 41, the grease G that overflows from between the male threaded portion 53 and the female threaded portion 43 only spreads into the gap between the outer peripheral surface of the tubular portion 54 and the inner peripheral surface of the bearing portion 42, and the grease G is unlikely to adhere to the lower end surface of the tubular portion 54 where the insertion hole 52 (fitting portion 52a) opens.

[0040] By providing the cylindrical portion 54 in the drive member 50 in this manner, the grease G applied to the male thread portion 53 of the drive member 50 is less likely to adhere to the periphery of the insertion hole 52 (fitting portion 52a) opening in the lower end surface of the drive member 50 (cylindrical portion 54) compared to a case where the cylindrical portion 54 is not provided, and therefore, it is possible to prevent the grease G from adhering to the tip of the small diameter portion 35a of the shaft 35 when the small diameter portion 35a is inserted into the insertion hole 52 of the drive member 50. As a result, it is possible to prevent a decrease in the joint strength between the drive member 50 and the shaft 35 due to the adhesion of grease G.

[0041] 4 , the assembly order of the three-way valve 26 of the present embodiment is not limited to the order in which the male thread portion 53 of the drive member 50 is threaded into the female thread portion 43 of the guide 41, and then the small diameter portion 35a of the shaft 35 is inserted into the bearing portion 42 of the guide 41 and inserted into the insertion hole 52 of the drive member 50. Alternatively, the order may be such that the shaft 35 of the shaft valve element 36 is first inserted into the bearing portion 42 of the guide 41, and then the small diameter portion 35a of the shaft 35 is inserted into the insertion hole 52 of the drive member 50 while the male thread portion 53 is threaded into the female thread portion 43 of the guide 41. In this case, providing the drive member 50 with the cylindrical portion 54 not only prevents the grease G applied to the male thread portion 53 of the drive member 50 from adhering to the tip of the small diameter portion 35a of the shaft 35 as described above, but also provides the effect of facilitating assembly of the three-way valve 26 as described below.

[0042] 5 is an explanatory diagram showing the assembly sequence of the three-way valve 26, in which the shaft 35 of the valve disc 36 is inserted into the bearing portion 42 of the guide 41, and then the male thread portion 53 of the drive member 50 is threaded into the female thread portion 43 of the guide 41. Fig. 5 shows a cross section of the valve disc 36 and other components cut along a plane including the center line of the shaft 35. First, Fig. 5(a) shows the state in which the shaft 35 of the valve disc 36 is inserted into the bearing portion 42 of the guide 41.

[0043] As described above, in the shaft valve element 36 of this embodiment, the protrusion 39 abuts against the lower end of the bearing portion 42 (the end portion facing the first valve element 34a), thereby restricting the upper limit of the axial movement of the shaft 35 (the limit of movement toward the drive member 50). The groove portion 35d (see FIG. 3) in which the O-ring 37 is mounted is arranged so that the O-ring 37 is positioned lower than the lower end of the female thread portion 43 when the shaft valve element 36 reaches its upper limit of movement. This prevents the O-ring 37 from protruding toward the female thread portion 43 even when the O-ring 37 moves axially together with the shaft 35, and prevents the O-ring 37 from being damaged by contact with the boundary between the bearing portion 42 and the female thread portion 43, the female thread, or the like.

[0044] 5(a), in the shaft valve element 36 of this embodiment, when the axial movement of the shaft 35 reaches its upper limit, the small diameter portion 35a at the tip protrudes upward from the female thread portion 43, whereas the upper end of the medium diameter portion 35b does not protrude upward from the female thread portion 43 and is located below the upper end of the female thread portion 43 (inside the female thread portion 43). When assembling the drive member 50, the small diameter portion 35a of the shaft 35 protruding from the female thread portion 43 is inserted into the insertion hole 52 of the drive member 50, and the female thread portion 43 is screwed into the female thread portion 43 of the guide 41.

[0045] At this time, if the driving member 50 does not have the cylindrical portion 54, the grease G adhering around the insertion hole 52 (fitting portion 52a) opening in the lower end surface of the driving member 50 may adhere to the tip of the small diameter portion 35a as described above (see FIG. 4(a)). In addition, as shown in FIG. 5(b), after the male thread portion 53 of the driving member 50 starts to be threaded into the female thread portion 43 of the guide, the medium diameter portion 35b having a rotation prevention shape is fitted into the fitting portion 52a, and it is necessary to align the fitting position of the medium diameter portion 35b and the fitting portion 52a while being restricted by the threaded engagement between the male thread portion 53 and the female thread portion 43, which makes assembly complicated.

[0046] In contrast, when the driving member 50 is provided with the cylindrical portion 54, as described above, the grease G applied to the male thread portion 53 is less likely to adhere to the periphery of the insertion hole 52 (fitting portion 52a) opening in the lower end surface of the driving member 50 (cylindrical portion 54) (see FIG. 4(c)), and therefore, it is possible to prevent the grease G from adhering to the tip of the small diameter portion 35a. Furthermore, as shown in FIG. 5(c), in the driving member 50 of this embodiment, the cylindrical portion 54 is protruded to a length that allows the fitting portion 52a on the inside of the cylindrical portion 54 to fit with the medium diameter portion 35b before the male thread portion 53 of the driving member 50 and the female thread portion 43 of the guide are threaded together. This allows the driving member 50, with the cylindrical portion 54 inserted inside the female thread portion 43, to be freely rotated around the axis of the shaft 35 without being restricted by the threaded engagement between the male thread portion 53 and the female thread portion 43, and the engagement position between the medium diameter portion 35b and the engagement portion 52a can be aligned, making assembly easier.

[0047] The three-way valve 26 of this embodiment has been described above, but the present invention is not limited to the above embodiment and can be embodied in various forms without departing from the spirit of the present invention.

[0048] For example, in the above-described embodiment, three-way valve 26 is used as a diverter valve in water heater 1. However, the use of three-way valve 26 is not limited to a diverter valve, and it may also be used as a mixing valve that combines the flow of hot water heated in heat exchanger 13 with the flow of clean water that has passed through bypass piping 22. In this case, the upstream side (heat exchanger 13 side) of hot water supply piping 21 relative to its connection with bypass piping 22 is connected to first port 32a, bypass piping 22 is connected to second port 32b, and the downstream side (hot water tap side) of hot water supply piping 21 relative to its connection with bypass piping 22 is connected to third port 32c. Furthermore, the application of three-way valve 26 is not limited to water heater 1, and it can be used to control various fluids as a diverter valve or mixing valve.

[0049] In the above-described embodiment, the small diameter portion 35a of the shaft 35 is inserted into the insertion hole 52 of the drive member 50 and joined by thermal welding. However, joining of the shaft 35 and the drive member 50 is not limited to thermal welding, and the shaft 35 may be press-fitted into the insertion hole 52 or bonded using an adhesive. In addition, in the above-described embodiment, the insertion hole 52 passes through the drive member 50 in the vertical direction (the axial direction of the shaft 35). However, when joining the shaft 35 and the drive member 50 by press-fitting or bonding, the insertion hole 52 does not have to pass through the upper end side of the drive member 50. Even in joining by press-fitting or bonding, if grease G adheres to the tip of the shaft 35, it will hinder the joining with the drive member 50. Therefore, by applying the present invention, it is possible to suppress a decrease in the joining strength.

[0050] In the above-described embodiment, the shaft 35, the first valve body 34a, and the second valve body 34b are integrally formed as the shaft valve body 36. However, the shaft valve body 36 does not have to be integrally formed, and the shaft 35, the first valve body 34a, and the second valve body 34b may be formed as separate bodies and joined together. However, if the shaft valve body 36 is integrally formed as in the embodiment, it is possible to omit a retaining ring, a push nut, and the like that would be required when joining the shaft 35, the first valve body 34a, and the second valve body 34b, which are separate bodies. This reduces the number of parts of the three-way valve 26 and simplifies assembly.

[0051] In the above-described embodiment, the protrusion 39 for restricting the upper limit of the axial movement of the stem valve element 36 (shaft 35) is provided on the stem valve element 36. However, it is also possible to arrange a plurality of protrusions projecting downward from the lower end of the bearing portion 42 of the guide 41 at approximately equal intervals in the circumferential direction, so that the upper limit of the movement of the stem valve element 36 is restricted by the first valve element 34a abutting against these protrusions. [Explanation of symbols]

[0052] 1...water heater, 2...combustion chamber, 3...burner, 4...Gas piping, 5...Main valve, 6...Proportional valve, 10... combustion fan, 11... spark plug, 12... flame rod, 13...heat exchanger, 14...exhaust port, 20...water supply piping, 21...hot water supply pipe, 22...bypass pipe, 23...water supply temperature sensor, 24...Flow rate sensor, 25...Water volume servo, 26...Three-way valve, 27...Hot water outlet temperature sensor, 28...Hot water supply temperature sensor, 30...Casing, 31...straight flow path, 32a...first port, 32b...second port, 32c...third port, 33a...first valve port, 33b...second valve port, 34a...first valve body, 34b...second valve body, 35...shaft, 35a...small diameter portion, 35b...medium diameter portion, 35c...large diameter portion, 35d...groove portion, 36...stem valve body, 37...O-ring, 38...guiding portion, 39...projection, 40...inner member, 41... Guide, 42... Bearing portion, 43... Female thread portion, 45... valve seat, 46... connecting portion, 50... driving member, 51... gear portion, 52... insertion hole, 52a... fitting portion, 53...male thread portion, 54...cylindrical portion, 60...cover plate, 60a...through hole, 61...motor case.

Claims

1. a three-way valve having a straight flow passage having one end communicating with a first port and the other end communicating with a second port, the straight flow passage having an intermediate portion communicating with a third port, the opening area of ​​a first valve orifice provided between the first port and the third port in the straight flow passage varying as a first valve disc approaches or moves away from the intermediate portion, and the opening area of ​​a second valve orifice provided between the second port and the third port varying as a second valve disc approaches or moves away from the intermediate portion, the first valve disc and the second valve disc being disposed at an end of a shaft that is movable in an axial direction parallel to the straight flow passage by being driven by a motor, and the first valve disc and the second valve disc moving together with the shaft along the straight flow passage, thereby changing the flow rate of fluid between the first port and the third port and the flow rate of fluid between the second port and the third port; a guide provided with a bearing portion through which the shaft is inserted and supporting the shaft so that the shaft is movable in the axial direction; a cylindrical driving member having a gear portion formed on an outer circumferential surface to which the drive of the motor is transmitted, and an end of the shaft opposite to the first valve body and the second valve body is inserted into and joined to an insertion hole opened in an end surface facing the first valve body and the second valve body; Equipped with Assuming that the drive member side of the shaft in the axial direction is an upper side and the opposite side where the first valve body and the second valve body are arranged is a lower side, The drive member has a male threaded portion below the gear portion, the male threaded portion having a male thread formed on an outer peripheral surface thereof, and the guide has a female threaded portion above the bearing portion, the female threaded portion having a female thread formed on an inner peripheral surface thereof, When the driving member rotates around the axis of the shaft by driving the motor in a state in which the male screw portion and the female screw portion are threadedly engaged with each other, the shaft moves in the axial direction in accordance with the engagement of the male screw portion and the female screw portion, A cylindrical portion having an outer diameter smaller than the inner diameter of the female thread portion and having the insertion hole on the inside thereof is protruded downward from the lower end surface of the male thread portion of the driving member. A three-way valve characterized by:

2. The three-way valve according to claim 1, The shaft is formed with a rotation prevention portion having a non-circular cross section perpendicular to the axial direction, a fitting portion having a shape that corresponds to the anti-rotation shape and fits with the anti-rotation portion is provided as part of the insertion hole on the inside of the cylindrical portion of the driving member, an upper end of the anti-rotation portion is located lower than an upper end of the female screw portion when the axial movement of the shaft inserted into the bearing portion of the guide reaches an upper limit; The cylindrical portion of the driving member is provided to protrude to a length that allows the fitting portion to fit into the anti-rotation portion before the male screw portion and the female screw portion are screwed together. A three-way valve characterized by:

3. The three-way valve according to claim 2, a groove in which an O-ring is fitted to seal the gap between the shaft and the bearing portion of the guide is formed on the outer circumferential surface of the shaft; The groove is formed at a position where the O-ring is positioned below a lower end of the female screw portion when the axial movement of the shaft inserted into the bearing portion of the guide reaches an upper limit and the upper end of the anti-rotation portion is positioned below an upper end of the female screw portion. A three-way valve characterized by:

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